Machine for producing tubular bends and coils and for expanding tubes



Nov. 8, 1927.

R. H. BGHLING MACHINE FOR PRODUCING TUBULAR BENDS AND cons AND FOR EXPANDING TUBES R. h. ah/m Patented Nov. 8, 1927.

. 1,648,161 UNITED ES PATENT OFFICE."

BUDOLF HIERQNYMUS BUHLING, OI. HAMBURG-STEINWARDER, GERMANY, ASSIGNOR 'I'O ROHRBOGENWERK GESELLSCHAFT MIT IBESCHRKNKTER-HAFTUNG, OF HAM- BURG, GERMANY, A FIRM.

MAGHIN E FOR PRODUCING TUBULAR BENDS AND COIL AND FOR EXPANDING TUBES.

Application filed January 25, 1927, Serial No. 163,509, and in Germany February 8, 1926.

piston rod is pulled inwardly, thus forcing,

the expanded end of the piston rod or the mandrel into the tubular work iece and thereby expanding it, or eventual y at the same time forming it into a bend corresponding to the shape of the mandrel. For

reducing the power hereby necessary the end of the work piece which is slipped over the mandrel will be preferably heated which may be done by any heating means. A hood made of refractory material is arranged to embrace that portion of the tubular workpiece to be heated together with the heating means. In the plants used heretofore the said hood and the burners of the gas flame together with the gas feeding pipes must be movable so as to be enabled to approach the cylinder each time after a bend is produced and cut off from the work-piece. The tubular work-piece generally will have a length of several metres and therefore the hood and the heating means must have a movability for a corresponding length, and this fact. makes it very inconvenient and inexpedient.v and an unsuitable construction of the hoodresults on account of;thefprojecting machine frame.

v By the. present invention the aim is to avoid the moving about of the hood and the heating means to the extent as heretofore when progressively producin bends or the like one after the other wit the result to enable the heating being effected always on the same spot for every bend produced from one single tubular work piece. According to the invention this result is secured by making the mandrel and the piston rod unmovable and arranging the cylinder to reciprocate, which is thus adapted to force the tubular work piece along the piston rod 81d over the mandrel. Even in this con- I, zontally struction, it is true,- the hood: must be moved backto some extent to permit the produced bend to be severed from the work piece, that is to say to allow the bend for the sake of being cut, to beaccessible outside the hood. However, this retraction of the hood is necessary only for a small and always the same degree and is neither inconvenient nor inexpedient, because there is no obstacle.

offered by the machine.

Moreover this retraction of the hood when severing the bend from the work piece may i also be avoided according to the invention, so that the hood and the heating device may remain always on the same spot. This greatly simplifies working. With this object 1n view a retraction cylinder is immovably mounted, its piston being connected with the piston of the pushing cylinder by a common piston rod. 'By the aid ofthis retractioncylinder the piston is operated by a pressure mediumso that it withdraws the mandrel from the hood to such an extent that the bend produced is convenientl accessible for being severed from the tubu ar work piece. By the movement of the piston of the retraction cylinder in opposite direction the mandrel will again be introduced into the hood. In reciprocating the retraction piston in both directions the pushing cylinder will participate in these movements.

In' the drawing Fig. 1 is a longitudinal section of the apparatus constructed according to the present inventiop, nd

Fig 2 is a similar view f a modification. For the pushing cylinder 6 having a considerable length a tracker-constitutes part of the machine frame and is adapted for horiiding said cylinder, which by rollers 0 1s adapted to run on said track a longitudinally. The piston rod' (2, which is firmly attached to the piston e within the cylinder 6, projects outwardly and at its free end is screwed to the mandrel; 7. From the right-hand end, Fig. 1, of the cylinder 6 projects a pipe which is attached to the piston e, and at its utmost end is immovably supion ported by a bracket h on the machine frame,

at which end the pipe is closed. It will be seen that by this construction the piston e and the mandrel f are unmovable. The pipe 9 is provided with an opening i close to the piston e and at the other end the pipe g has a branch pipe 70 by which a pressure medium (for instance compressed water)- may be introduced. Within the cylinder g a second thinner pipe Z is attached to the piston e and projects out through the closed end of the pipe g, where this pipe is resting in the bracket h. At the point, where the pipe Z is attached to the piston 6, it communicates with a assage m leading into the space in front 0 the piston 0. By the. means described above the compressed Water may be allowed to enter the cylinder either on the left-hand side of the piston e or on hand side of the piston to either push out the movable cylinder or to retract it.

The tubular work piece being slipped on the piston rod (1 will be pushed towards the in Fig. 1 by left, when the cylinder 6 is moved in this direction by compressed water entering the cylinder on the left-hand side by the pipe Z. The pipe thus being forced forwardly will be urged over the mandrel f thus.being turned into a bend at this end. Whenfit is necessary to sever the newly formed bend from the tubular work iece thehood j is retracted outwardly. A ter taking off the bend the hood is moved into its normal position again, and then the forward movement of the cylinder is continued to again force the forward end of the tubular work piece over the mandrel. I 7

In the drawing machine. shown in Fig. 2 the tube g is not attached to the bracket 72. but at its free end is provided with a second piston n, which is adapted to, reciprocate within a retraction cylinder 0 firmly mounted on the bracket h. The narrow pipe 1 within the pipe g passes out through the end of the retraction cylinder. 0. The cylinder 0- at its utmost end is connected with the pipe p for feeding compressed water.- A further branch pipe r on the other end of the cylinder 0 1s also provided for feeding compressed water.

The firm hold of the piston rod (2 or the mandrel f is effected in the machine shown the bracket h, and by compressed water within the retraction cylinder o of the right-hand side of the piston n in the construction shown in Fig. 2. The stroke of the piston n within the retraction cylinder 0 is so dimensioned that the piston on its movement towards the left-hand end of the retraction cylinder draws the mandrel iiafiiciently backwardly fromthe heating Whian on account of the forward movement of the cylinder b a bend is produced, compressed water is introduced into the retraction cylinder 0 on the left-hand sideof the .piston n, while on the right-hand side compressed water is allowed to escape, thus forcm the piston n and also the mandrel f towar s the right, that ing it from the hood. The cylinder 7) participates in this movement so that the pisthe rightcompressed medium in front of or is to say, withdrawton 0 remains in its position. When the bend thus produced is severed from this tubular work piece compressed water is allowed to enter the retraction cylinder on the right-hand side of the piston n, while the compressed ,water on the other side of the piston n is allowed to escape. Thus the piston n and the mandrel f are moved towards the left, the latter entering again the hood, the cylinder 6 also being moved into its former position, which it had when the bend was produced.

The pipe Z may open out into the space of the right-hand side of the retraction cylinder, so that the introduction of compressed water into the cylinder e on the left-handefiected by compressed water side may be being forced into-the pipe p passing over the right-hand side of the retractioncylinder.

I claim 1. A machine for producing tubular bends, coils and the like or for expanding tubes, comprising a cylinder, a piston fitting within said cylinder, a piston rod projecting out through the end wall and adapted to carry and guide the tubular Work piece, a mandrel at the free end of said piston rod, the said cylinder adapted to reciprocate and the said piston being adapted to-be firmly held while the cylinder is operating to push the tubular work piece along said piston rod, and means to introduce a compressed medium into the cylinder in front of or behind the said piston.

2. A machine according to claim 1, comprising a second cylinder mounted, a piston slidable within said second cylinder and connected with the piston of the first-named cylinder, and means 'to feed a compressed medium in front of or behind the piston of the said second cylinder.

3'. A machine according to claim 1, comprising a second cylinder immovably mounted, a piston slidable within said second cylinder and connected with thepiston of the first-named cylinder, means to feed a behind the piston of the said second cylinder, a tubular piston rod connecting the two pistons and adapted to feed the compressed medium into the first-named cylinder behind its piston, a tube connected with the piston of the first-named cylinder of a smaller diameter than the said tubular piston and passing therethrough and also'through the of, the cylinderimmovably piston of the second-named cylinder and a passage within the first-named piston to connect the last-namedtube with the space of the first-named cylinder in front of its piston.

In testimony whereof I have signed my name to this specification.

- RUDOLF mraommus Minute. 

